Analog-to-digital tester
First Claim
1. In a digital tester havig functions to measure at least direct current voltage, alternating current voltage and resistance, the improvement comprising:
- a signal conditioning means for generating a DC voltage output in proportion to a quantity of measured input voltage said signal conditioning means including first and second attenuation means for providing two levels of attenuation of said measured voltage input to said signal conditioning means, said first and second attenuation levels differing by a multiple of one hundred, and attenuation switching means cooperating with said first and second attenuation means for selecting one of said attenuation means corresponding to the magnitude of said input voltage measurand,analog-to-digital (AD) converter circuit means for converting the analog output signal from said signal conditioning means into a digital value, said analog-to-digital converter means including a switching means for changing-over sensitivity of said analog-to-digital converter circuit means to 1/1 or 1/10, by combinations of attenuation and sensitivity levels the ranges of said measurand values which can be measured and displayed with full scale sensitivity are four; and
display means for displaying digital numbers corresponding to the output from said analog-to-digital converter circuit means.
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Accused Products
Abstract
An analog-to-digital tester having at least two distinct ranges of full scale sensitivity is provided. The tester includes signal conditioning means for receiving an analog measurand and digital display for displaying a value representative of the measurand. The signal conditioning means includes first and second attenuation levels differing by a multiple of at least 100 and circuit means for selecting the attenuation level corresponding to the magnitude of the measurand. The analog-to-digital converter circuit has full scale sensitivity over a first range and additionally full scale sensitivity over a second range ten times greater than the first range and includes range detecting means for detecting the magnitude of the measurand applied to the signal conditioning means and in response thereto selects the first or second full scale sensitivity range to thereby apply a digital value representative of the measurand to the digital display. Combinations of selected sensitivity and attenuation levels provide at least four ranges of measurand values for display. Measurands include AC voltage, DC voltage and resistance.
21 Citations
19 Claims
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1. In a digital tester havig functions to measure at least direct current voltage, alternating current voltage and resistance, the improvement comprising:
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a signal conditioning means for generating a DC voltage output in proportion to a quantity of measured input voltage said signal conditioning means including first and second attenuation means for providing two levels of attenuation of said measured voltage input to said signal conditioning means, said first and second attenuation levels differing by a multiple of one hundred, and attenuation switching means cooperating with said first and second attenuation means for selecting one of said attenuation means corresponding to the magnitude of said input voltage measurand, analog-to-digital (AD) converter circuit means for converting the analog output signal from said signal conditioning means into a digital value, said analog-to-digital converter means including a switching means for changing-over sensitivity of said analog-to-digital converter circuit means to 1/1 or 1/10, by combinations of attenuation and sensitivity levels the ranges of said measurand values which can be measured and displayed with full scale sensitivity are four; and display means for displaying digital numbers corresponding to the output from said analog-to-digital converter circuit means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A digital tester for measuring at least voltage comprising:
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signal conditioning means, said signal conditioning means including; input terminals for application thereto of analog voltages to be measured; an operational amplifier having an input resistance, and feedback resistance from output to input, said input terminals connecting said measured voltage to said operational amplifier through said input resistance; and means to vary said feedback resistance by selected magnitudes, whereby the gain in output of said operational amplifier is varied in selected magnitudes by 100 to 1; analog-to-digital conversion means for converting the analog output of said operational amplifier to a quantified signal indicative of the input voltage; amplifier means intermediate said operational amplifier and said analog-to-digital conversion means, said amplifier means having selectable gains of 1 or 10, said operational amplifier output signal being inputted to said selectable gain amplifier means, the output thereof being input to said analog-to-digital conversion means; display means for displaying said quantified signal, said quantified output of said analog-to-digital conversion means depending in magnitude on both the selected gain of said intermediate amplifier means and the selected gain of said operational amplifier and four ranges with full scale sensitivity are provided. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. In an analog-to-digital tester including input means for receiving an analog value measurand and digital display means for displaying a digital value representative of the measurand, the improvement comprising analog-to-digital converter circuit means having at least full-scale sensitivity over a first range and full-scale sensitivity over a second range that is ten times greater than said first range, said analog-to-digital converter means including range detecting means for detecting the magnitude of said analog value measurand and in response thereto being adapted to select one of said first and second range of full-scale sensitivity to thereby apply to said digital display means a digital value representative of said analog value measurand, said input means including first and second attentuation, means to provide two levels of input attentuation;
- said first and second attenuation levels differing by a multiple of one hundred and switching means intermediate said first and second attenuation means for selecting an attenuation level corresponding to the magnitude of said analog voltage measurand, the range of said measurand values that are measured and displayed with full scale sensitivity is at least four, said switching means being a manually operated two-position switch for permitting manual selection of one of said first and second attentuation means.
- View Dependent Claims (16, 17, 18, 19)
Specification